1. Field of the Invention
The present invention relates to a mount device for dental implant, and more particularly, to a mount device for dental implant used to place a fixture in an alveolar bone.
2. Description of the Related Art
Originally, implant means a replacement to restore human tissues when the human tissues are lost. In the dentistry, the implant means transplantation of an artificial tooth root. The dental implant is a state-of-the-art treatment which helps the restoration of a function of a tooth by placing a tooth root made of titanium that does not show organ rejection in a bone where a tooth is missing and fixing an artificial tooth thereon, to replace the root of the missing tooth. For a general prosthesis or denture, neighboring teeth and bone are damaged as time passes. However, the dental implant does not damage neighboring tooth tissues and provides the same function or shape of a natural tooth without generating a decayed tooth, so that it can be used semi-permanently.
The dental implant treatment is a revolutionary development that is compared to the Industrial Revolution in the field of dentistry. Due to this development, a variety of implants are introduced into the market so that scores of implants including domestic and foreign implants exist in the market. Since the various types of implants have different structures and shapes, many dentists are confused and have difficulty in treatment. Such difficulty sometimes makes an implant treatment a failure.
Thus, making the implant treatment easier and reducing a treatment time are necessary jobs to achieve for both of a dentist and a patient. In the implant treatment, not only a step of easily placing an implant but also a step of easily removing a mount device that enables placing of the implant is important.
In the structure of a dental implant, as shown in FIG. 1, a fixture 150 that is an artificial tooth root is first placed in upper and lower jawbones 180 (hereinafter, referred to as the alveolar bone) like a root of a natural tooth. The fixture 150 is osseointegrated to be completely fixed to the alveolar bone 180. After the osseointegration, an abutment 190 is connected to the fixture 150 of the dental implant using an abutment screw (not shown) and an artificial crown 170 is mounted thereon, so that an implant artificial tooth is completed. The fixture 150 of the dental implant passes through a compact bone having a relatively higher bone density and placed in a spongy bone 180b having a relatively lower bone density.
When the fixture of a dental implant is placed in the alveolar bone, a mount is coupled to the fixture using a mount screw. An upper end portion of the mount screw is inserted in a handpiece through a handpiece connector and rotated by a strong rotational force so that the fixture is placed in the alveolar bone.
However, a coupling hole formed in the alveolar bone in advance for the placement of the fixture has a diameter smaller than the outer diameter of a screw formed on the fixture. Also, since the fixture is placed in the alveolar bone while making a screw therein. Thus, for a fixture in which the fixture and the mount are coupled in a conical connection, a strong torque is generated between the inner surface of the fixture and the outer surface of the mount during the placement of the fixture so that the fixture and the mount closely contact each other.
When there is no special structure to remove a state in which the inner surface of the fixture 150 and the outer surface of the mount closely contact each other by the strong torque applied therebetween after the fixture is placed, if the handpiece is rotated in the reverse direction for the placement to separate the mount device from the fixture, not only the mount device but also the fixture is pulled out.
Thus, a structure to prevent the above phenomenon is needed. Although a variety of structures to disassemble the mount device only after the placement of the fixture have been suggested, it is a problem that the structure is complicated in most cases.
To consider the problem, a mount device 101 for a dental implant having a structure as shown in FIGS. 2 through 5 has been introduced. The mount device 101 includes a mount screw 110 including a body portion 111 having a first screw portion 112 where a right screw is formed at a lower end portion thereof and a second screw portion 113 where a left screw is formed at a position separated a predetermined distance upward from the first screw portion 112, and a mount 120 provided on an inner side wall of an insertion hole 122 where a second inner screw portion 123 that can be screw coupled to the second screw portion 113 of the mount screw 110 is formed by penetrating the same.
In the structure, when the fixture 150 is placed, the second inner screw portion 123 of the mount 120 is coupled to the second screw portion 113 of the mount screw 110 and the first screw portion 112 of the mount screw 110 is coupled to a first inner screw portion 152 of an inner hole 153 of the fixture 150. When the mount screw 110 is rotated clockwise as shown in FIG. 2 using a handpiece 160 which connects the mount screw 110 via a handpiece connector 140, the mount screw 110 does not relatively rotate against the fixture 150 and is rotated together with the fixture 150.
This is because, in addition to the screw coupling between the first screw portion 112 of the mount screw 110 and the first inner screw portion 152 of the fixture 150, when the mount screw 110 is rotated clockwise using the handpiece, since the second screw portion 113 of the mount screw 110 is a left screw, the mount 120 is moved in a direction such that the second screw portion 113 of the mount screw 110 is separated from the second inner screw portion 123 of the mount 120. As a result, as shown in FIG. 2, an inclined surface 121 of the mount 120 and a fixture inner inclined surface 151 closely contact each other so that a friction force is applied therebetween.
That is, in addition to the screw coupling between the first screw portion 112 of the mount screw 110 and the first inner screw portion 152 of the fixture 150, the frictional force between the inclined surface 121 of the mount 120 and the fixture inner inclined surface 151, where a contact area is large, acts as a main force to rotate the fixture 150, thus rotating the fixture 150 together with the mount screw 110. As the fixture 150 is placed in the alveolar bone 180 to a predetermined depth while rotates, the placement is completed.
Next, in order to remove the mount device 101 after the fixture 150 is placed, a mount holder 130 is coupled to the mount 120 as shown in FIG. 3. The mount screw 110 is rotated counterclockwise in the opposite direction for the placement while either the mount hole 130 prevents the mount 120 from rotating or the mount holder 130 rotates the mount 120 clockwise, Then, the mount 120 is move upward as shown in FIG. 4 such that the second screw portion 113 of the mount screw 110 and the second inner screw portion 123 of the mount 120 are screw coupled to each other. Accordingly, the state of the inclined surface 121 of the mount 120 pressed against the fixture inner inclined surface 151 is removed so that the frictional force is no longer applied therebetween. Thus, only the mount screw 110 relatively rotates with respect to the fixture 150 placed in the alveolar bone and is disassembled from the fixture 150.
The reason for fixing the mount 120 using the mount holder 130 will be described in detail for a better understanding. Assuming that the mount screw 110 is rotate counterclockwise without fixing the mount 120 using the mount holder 130, since the inclined surface 121 of the mount 120 and the fixture inner inclined surface 151 closely contact each other after the replacement, the force rotating the mount screw 110 counterclockwise makes the frictional force between the inclined surface 121 of the mount 120 and the fixture inner inclined surface 151 act in a direction to rotate the fixture 150 counterclockwise and the mount 120 clockwise.
As mentioned above, since the frictional force is a main force to rotate the fixture 150, the frictional force acting in a direction to rotate the fixture 150 counterclockwise means that the mount screw 110 and the fixture 150 rotate together so that the fixture 150 finally comes out as well.
However, when the mount screw 110 is rotated counterclockwise while fixing the mount 120 using the mount holder 130 or rotating the mount 120 clockwise, the force rotating the mount screw 110 counterclockwise makes the frictional force between the inclined surface 121 of the mount 120 and the fixture inner inclined surface 151 act in a direction to support the counterclockwise rotation of the fixture 150, that is, clockwise, and in a direction to rotate the mount 120 counterclockwise. The frictional force acting in a direction to rotate the fixture 150 counterclockwise means that the rotation of the fixture 150 with the mount screw 110 is obstructed by the frictional force and the fixture 150 maintains a placed state without being rotated counterclockwise.
In the meantime, in the conventional mount device for a dental implant, since the second screw portion 113 of the mount screw 110 is formed so closely to a head portion 115, when the fixture is placed in the alveolar bone and the mount device 101 is removed, if the handpiece 160 is rotated counterclockwise while fixing the mount 120 using the mount holder 130 or rotating the mount 120 clockwise using the mount holder 130, the mount 120 is moved upward toward the mount screw 110 by the rotation of the mount screw 110. Then, before the screw coupling between the second screw portion 113 of the mount screw 110 and the second inner screw portion 123 of the mount 120 is removed, the lower end surface of the head portion 115 of the mount screw 110 and the upper end portion of the mount 120 closely contact each other as shown in FIG. 5 so that the handpiece 160 connected to the mount holder 130 cannot be rotated any longer. Thus, it is a problem that, only when the rotation of the handpiece 160 is stopped and the mount holder 130 is removed from the mount 120, the mount device 101 can be removed by continuously rotating the handpiece 160 counterclockwise.
Hence, an implant operation is made very inconvenient and the inconvenient operation is performed inside a mount of a patient which is very narrow and difficult to view so that the pain of patients undergoing operations increases and dentists are also inconvenienced. In particular, since the mount holder 130 is used inside the mount of a patent, it is difficult to make the mount holder 130 thick. Thus, when an open ended wrench having an insufficient thickness is used as the mount holder 130, the open portion is easily widened, which makes the use of the open ended wrench inappropriate. Alternatively, when a slugging ring wrench is used, since the handpiece connector 140 and the handpiece 160 need to be completely separated from each other to detach the mount holder 130, the implant operation is made very inconvenient, the operation time remarkably extends, and the dentists are inconvenienced.
As shown in FIGS. 2 through 5, according to the conventional technology, since the mount 120 is conical such that the outer diameter of the lower end portion is less than that of the upper end portion, and the lower end portion of the mount 120 is inserted in the fixture 150, the upper end portion of the fixture 150 has a thin thickness. When the mount 120 is inserted in the fixture 150 and contacts the same, since the mount 120 applies a force in a radial direction of the fixture 150, the upper end portion of the fixture 150 is frequently damaged.